Device to regulate the direct current motors for the coil rolls of a rewinder



ne 3, 1958 R. s HLER 2,837,705

DEVICE TO REGULATE T DIRECT CURRENT MOTORS FOR THE COIL ROLLS OF A INDERFiled Aug.

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ATTORNEYS Unite St tes Patent DEVICE TO REGULATE DIRECT CURRENT MOTORSFQJR THE COIL ROLLS OF A REWINDER Roland Spnhler, Wettingen,Switzerland, assignor to Aktiengesellschatt Brown, Boveri & Cie, Baden,Switzerland, a joint-stock company Application August 19, 1955, SerialNo. 529,455

Claims priority, application Switzerland August 21, 1954 4 Claims. (Cl.318-7) This invention relates to a device to regulate the direct currentmotors of the coil rolls of a rewinder at constant tension and velocityof the goods. Such re- Winders are e. g. used for the rewinding offabrics in dye works, as well as for the rewinding of paper, foils;wires, tapes and the like.

With this rewinding it is desirable that the goods move at steadyvelocity during the entire rewinding process. Besides, the tension towhich the goods are exposed during the entire rewinding process must beconstant. While the diameter of the batching roll is growing and thediameter of the unwinding roll is diminishing, the circumferential speedof the rolls must be kept constant. Accordingly the R. P. M. of thebatching roll progressively increases and that of the unwinding rolldiminishes. With increasing diameter of the batchingroll, the windingmoment increases while the unwinding moment decreases. Accordingly therolling momentum of the driving motor must be increased While thebraking motor running as generator must obtain a reducing rollingmomentum to maintain the constant motion of the goods.

Devices to regulate the direct current motors for such rewinders areknown. Yet they require considerable costs. According to the presentinvention, gas discharge tubes are preferably used as regulatingdevices. Of course, also other regulating devices, equivalent to saidtubes can be used, e. g. high vacuum tubes, magnetic amplifiers, machineintensifiers, etc.

The invention consists in that the rotors of the direct current motorsare jointly fed and their induction Winding is fed from the alternatingcurrent supply through one gas discharge tube inserted in push-pull foreach rotor. In the rotor current circuits one rheostat is inserted foreach rotor, and the governing of the tubes is effected in phaseopposition through a resultant control voltage which is composed of apredetermined voltage, an effective voltage dependent on the rotorcurrent which was taken oil the rheostats, and a voltage which is afunction of the machine speeds so that the tension and the velocity ofthe goods remain approximately uniform. The invention is explained indetail by way of a preferred embodiment illustrated in electricalschematic diagram in the accompanying drawing.

With reference now to the drawing, 21 and 23 are batching and unwindingrolls for the goods to be rewound, e. g. fabrics when passing through adye reservoir. The rotors l and 2 of direct current dynamo electricmachines are coupled respectively with these rolls. The feeding of themachines is eflected jointly through the direct current generator 3,driven by the alternating cur-.

rent motor 4. The output voltage of the generator is adjustable by thefie d rheostat 9, and the polarity of the output can be reversed bymeans of the switch 19 to efizect reversal of the direction of rotationwhen the goods move back. The field coils 5 and 6 of both machines arefed, from an alternating current supply over one gas discharge tube 7 or8 for each coil and the transformers 25 and 26. The tubes are installedin push-pull so that Patented June 3, 1958 during the increase of thefield current in one coil 21 reduction appears in the other coil andvice versa. For this purpose, the regulation of the gas discharge tubesis eflected in phase opposition through pre-amplifiers 27 and 28 by apositive or negative control voltage Vc, acting on the terminals 29a and30a of the rheostats 29 and 30.

in series with the rotors 1 and 2 there are installed identical shunts10 and 11. On these shunts there is taken oil over the terminals Ida and11a a signal voltage which is proportional to the difilerence of therotor currents When both machines work as motors, respectively to thetotal when one machine operates as generator and the other Works asmotor. This voltage is applied in opposition to a predetermined value ofvoltage taken oir a control rheostatfl, fed by direct current. Similarlythe control voltage can be suitably influenced by a correcting voltagewhich is dependent on the dilterent rotation speedsof the motors. Thisvoltage is produced by two tachometer dynamos 13 and 1 which are coupledrespectively with the motors 1 and 2; said dynamos are engaged inopposition in the regulating circuit over the potentiometer 15.Consequently the control voltage Va is the resultant of the rotorcurrents of motors 1 and 2 as taken from terminals 16a, 11a, thepredetermined value of voltage taken of control rheostat 12, and thecorrecting voltage which is a function of the rotational speeds of themotors. The resultant control voltage V0 is applied to the terminals29a, of the pro-amplifier circuit. The proper polarity of the controlvoltage may be established by means or" the polarity reversal switch 18.

The mode of operation is as follows: During a winding process thedriving machine operates as a motor while the braking engine acts as agenerator. With constant tension and constant velocity of the goods, theoutput of the rewinding process is constant for the entire length of thegoods. The generator 3 supplies the electric and mechanical power lossof the machines including the rewinder. The rate of revolutions of themachines is fixed on the average by the armature voltage of thegenerator 3 and can be adjusted by way of the rheostat 9. The currentspassing through the rotors 1 and 2 are a measure for the winding tensionapart from the friction. The mechanical losses are substantiallyproportional to the rate of rotations of the motors.

Supposing that the goods pass in the direction of the arrow. Thus themachine 2 operates as a motor and the machine 1 acts as a generator.Across the erminals Ida and 11a, there appears a voltage correspondingto the total of the motor current and the generator current. Thecurrents are, apart from the friction, a measure for the rotationalmoments of both machines. The voltage appearing on the terminals Fla/11ais a measure of the winding tension. This voltage is compared with theme determined voltage o the potentiometer i2 and their difference isapplied e r as a positive or negative signal on the driving tubes 27, 28connected in phase opposition. In interrelation to the size and thepolarity of this control voltage Vc, the field current of coils and 6 isamplified or diminished respectively or vice versa. The gainamplification is selected so that with increasing load rotation momentumthe E. M. F. of the motor grows at the appropriate rate even at arelatively slight increase in the rotor current. The inverse processtakes place with the generator. The machine currents change to arelatively minor extent than do the induction currents and thus themagnetic field of the machines. The rate of rotation itself is adaptedto the respective rewinding state by the simultaneous amplification or rduction respectively of the relative fields in usual way.

The additional voltage on the potentiometer 15 corrects approximatelythe mismatching influences of "the mechanical friction. That isnecessary because the currents combine through the shunts and 11 of thetension-proportional current and a current to overcome the frictionforce. The friction power and thus its friction currents are in firstapproximation proportional to the rate of motor revolutions. Theresulting mismatching additional voltage reduction on the shunts 1G and11 can be compensated by both tachometer-dynamos 13 and 34 whose voltageis proportional to the rate of rotation. The difference in voltage,between effective and theoretical value which finally regulates thetubes is, in this way, free of mismatching friction influences.

Alternately connected in parallel with the input resistances 29, bymeans of switches controlled by relay 17 are resistances 16 and 16awhich serve to achieve a certain non-symmetry in the control of themodulation currents. In this manner it may be achieved that the velocityof the goods remains constant during the entire winding process. Apartfrom nonlinearity and saturation influences, the velocity of the goodswould somewhat fall by the end of the winding process. By the asymmetricinsertion of the parallel resistances 16 or 16a at the moment of equalwinding diameter, this decrease in the velocity of goods can becorrected. It may occur that by the influence of the nonlinearity of theregulation and iron saturation the relay 17 must also be switched atanother period than c. g. at the moment of the reversing. The switchingof the relay 17 can, in this case, be made dependent on the differencevoltage of the tachometer-dynamos 13 and 14 on or from the activity ofthe reversing switch.

The use of two equal shunts 14 and 11 in each rotor circuit according tothe switch indicated above, shows the further advantage that themismatching influences of copper and iron losses are eliminated inadvance, since the mismatching volta e components originating from theelectric losses are approximately ofi-setin'the resulting actual valuevoltage.

The device according to the invention is characterized by a highaccuracy of the regulation at relatively inexpensive cost. The inventionis particularly suitable for modern dye rewinders in the textileindustry. Special meters of speed and protecting equipment, e. g.pendulurn rollers; scanning rollers etc. are not needed. The deviceallows, above all, with a small pressure of goods, where the influenceof the friction is especially strong, still an accurate regulation. Afurther advantage consists in that apart from the motors, there do notexist any mechanically driven components such as belts,

1 claim:

1. Aspeed regulating system comprising adirect. current motor and adirect current generator having their armature circuits connected inparallel with a direct current source; means providing a direct currentsignal voltage which is a function of the difference of the armaturecurrents of said direct current machines; means providing a directcurrent correcting voltage which is a function of the difference of therate of revolutions of said direct current mach nes; means for comparingsaid signal voltand sait correcting voltage with a predetermined directcurrent voltage to produce a resultant direct current control voltage; apair of electron tubes connected in push-pull relationship, the fieldwinding of 'said'direct current motor being connected in parallelacross-one of said electron tubes and the field winding of said directcurrent generator being connected in parallel across the other of saidelectron tubes; means for applying alternating current voltages upon thefield windings or" said motor and said generator respectively; and meansfor applying said direct current control voltage upon the control gridsof said electron tubes so that during the increase of the field currentin the field Winding of one of the direct current machines a reductionin field current will be efiected in the field winding of the otherdirect current machine.

2. A speedregulating device as defined in claim 1 wherein said means forproviding said correcting voltage comprises a first tachometermechanically connected to the motor shaft and a second tachometermechanically connected to the generator shaft, said tachometers beingconnected in series opposition.

3. A speed regulating system as defined in claim 1 and further includingmeans for adjusting the degree of regulation of the field windings ofthe direct current machines comprising switch-controlled resistor meansconnected in parallel with said electron tubes.

4. A speed regulating system as defined in claim 3 wherein goods areunwound from a supply reel mechanically connected to the shaft of thedirect current generator and said goods are Wound upon a take-up reelmechanically connected to the shaft of the direct current clutches,cog-wheels, etc. so that the wear is reduced to a minimum.

motor, and wherein said switch-controlled resistor means are actuatedwhen the diameters of the goods on the reels are momentarily equal sothat'constan't linear velocity of the goods will be maintained.

References (Jilted in the file of this patent UNITED STATES PATENTS1,991,088 Forbes -Q Feb. 12, 1935 2,060,672 Heymann Nov. 10, 19362,168,777 McCreary Aug. 8, 1939

